PROXIMATE VALUES, INCIDENCE OF AFLATOXIGENIC MOULDS AND CONTROL USING NON-TOXIGENIC FUNGI ISOLATED FROM SORGHUM OBTAINED FROM SOME MAJOR MARKETS WITHIN JOS METROPOLIS, NORTH-CENTRAL, NIGERIA

Abstract

The development of aflatoxigenic fungi on grains is accountable for adverse health consequences in human and animals. The aim of this study was to determine proximate valves, the incidence of aflatoxigenic moulds and attempt control with nontoxigenic fungi isolated from sorghum. In this study, forty (40) samples of sorghum were purchased from some major markets and the proximate values determined using standard methods. They were evaluated for fungal contaminants using conventional mycological techniques. The aflatoxin production potentials of the fungal isolates were determined on Yeast Extract Sucrose Agar Medium supplemented with 0.3% cyclodextrin and 0.6% Sodium Desoxycholate (YCSD) and also on coconut agar medium. The inhibitory activity of non-toxigenic fungi on the aflatoxigenic Aspergillus flavus strain was then determined. While the incidence of aflatoxigenic moulds was also determined, the total aflatoxin from the sorghum was determined using ELISA. Red sorghum presented the least moisture 6.99±80 and highest was white sorghum with 8.27±0.25. Eight moulds and one yeast was isolated from these studies: Saccharonycetes cerevisae, Penicillium chrysogenum, Rhizopus stolinifer, Aspergillus niger,  Aspergillus flavus, Aspergillus parasiticus, Aspergillus fumigatus, Fusarium sp. and  mucor spp.  The moulds count range was 3.6×10²  ± 32.7 - 2.4 ×10³ ±70.9 CFU/g in white sorghum. Red sorghum presented maximum count of 8.8×10²±59.9 - 1.2×10³ ± 80.3 CFU/g.  Aspergillus flavus had the incidence of 14/20 and 11/20 for red and white sorghum respectively. Aspergillus parasiticus had incidence of 11/20 in red sorghum and 13/20 in white sorghum. Incidence of aflatoxigenic Aspergillus flavus recorded 5/20 and 7/20 in red and white sorghum respectively. All the samples had different aflatoxin levels. The highest was 6.3 µg/kg and the least was 1.2 µg/kg. While all the grain samples were within the 10 µg/kg, fifteen percent (15.0%) of the total samples exceeded the 4.0 µg/kg EU recommended limit. There was no inhibition of aflatoxin production by any of the eight non-aflatoxigenic fungi after incubation with aflatoxigenic Aspergillus flavus. The occurrence of aflatoxigenic moulds and the detection of aflatoxins in this study emphasize the need for effort to eradicate their occurrence in foods. Awareness on grain handling and aflatoxins is hereby advocated.